Method and apparatus for conditioning air in railway passenger cars



w. J. MADDEN 2,018,274

METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Oct. 22, 1935.

Filed July 10, 1933 7 Sheets-Sheet l I. INVENTOR; William .I Miuidan, BY f A TTORNEYS.

w. J. MADDEN 2,018,274

METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Oct. 22, 1935.

7 Sheets-Sheet 2 Filed July'lO, 195s FIG ZIZ INVENTOR:

WITNESSES: @34 2) William J: mam

A TTORNEYS.

a. 22, 1935. w J, MADDEN 2,018,274

METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Filed Jill 1955 7 Sheets-Sheet 3 FIG: I]:

!NVENTOR:-

WITNESSES: 479 4 fl Williml Mmidan,

w. J. MADDEN 2,018,274 METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Oct. 22, 1935.

Filed Jul 10, 1933 I 7 Sheets-Sheet 4 INVENTOR: William 1 man,

BY I

WHOM

WITNESSES:

Oct. 22, 1935. w. J. MADDEN METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Filed July 10, 1933 7 Sheets-Sheet 5 gm g U -FIG IZZ. -42 K WW 1 M 3: ML .51

52 WVENTOR:

William I mmm,

' .HG'TM Er A i; g i ATTORNEYS.

Oct. 22, 1935. 'w. J. MADDEN 2,018,274

METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Filed July 10, 1935 7 Sheets-Sheet 6 FIGXW.

21/ w a a2 20 20 20 20 hulllll WITNESSES:

I N VEN TOR: William 1 YWafld/ I 5 721 %TORNEYS.

0a. 22, 1935. w. J. MADDEN I 2,018,274

METHOD AND APPARATUS FOR CONDITIONING AIR IN RAILWAY PASSENGER CARS Filed July 10, 1933 7 Sheets-Sheet 7 WI TNESSES:

' INVENIOR: 7 William I Mammy A TTORNEYS.

Patented Oct. 22, 1935 METHOD AND APPARATUS FOR CONDI- TIONING AIR CARS IN RAILWAY PASSENGER William J. Madden, Lansdowne, Pa. Application July 10, 1933, Serial No. 679,745

' 6 Claims. (01. 98-10) This invention relates to a system for the conditiomng of air in railway passenger cars, such as day coaches, sleeping cars, dining cars of other railway vehicles in which people assemble, and embraces in its preferred form not merely the treatment of air to obtain the desiredtemperature and humidity, but also other factors of air conditioning, including particularly the circulation and filtering of air in the passenger space and the replenishment of used air with fresh air.

In my co-pending application for U. S. Letters Patent, Serial No. 679,747, filed Julyv 10, 1933,

now Patent No. 1,986,978, I have described those features of my invention which are applicable generally to the cooling of air in an enclosure to insure comfort to the occupants in hot weather. The present application is directed to those features of my invention which are particularly applicable to the conditioning of railway passenger cars, and which have relation to heating and ventilating as well as cooling the air in-the' passenger space.

Generally stated, the object of the invention is to provide in a railway passenger car a method of and means for efficiently and economically conditioning the air in the passenger space, thereby iiisuring comfort to the occupants under varying atmospheric conditions.

A more specific object of the invention is to provide a system of air circulation which will cause the body of air in the passenger space to move longitudinally in parallel strata toward the end of the car and to be conditioned and mixed with regulated quantities of air from the outside atmosphere, thereby maintaining uniformity of temperature in all regions of the passenger space with avoidance of dead airpockets.

Another object of the invention is to provide a system of continuous air circulation inwhich the volume of air flowing through the system is increased or diminished by thermostatic control means responsive to changes in the interior tem-' perature of the car with their action modified at certain seasons of the year-by the prevailing.

temperature difference between the air within and without the car.

Other objects and advantages characterizing my invcntio'mincluding those derived from simplicity and economy of manufacture and efficiency of operation, will become more fully apparent from the description hereinafter set forth of one embodiment or example of the practice of the invention, having reference to the accompanying drawings. Of the drawings;

Fig. I represents a plan view of the interior of a railway passenger car embodying my invention.

Fig. II. represents a side elevation of one end of the railway car with portions thereof broken 5 away to illustrate the front of the air cooling cabinet.

Fig. III represents an end view of the car with portions thereof shown in cross section as indicated by the lines III-III of Fig. I.

Fig. IV represents an enlarged front view of the cooling cabinet with a portion broken away to illustrate the interior thereof.

Fig. V represents a vertical cross section of the same, taken as indicated by the lines VV 15 of the cooling cabinet, taken as indicated by the lines IX-IX of Fig. V, and showing one of the damper operating shafts.

Fig. X. represents a cross section, taken as indicated by the lines X-X of Fig. IX, and showing one of the dampers of the cooling cabinet in detail. v

Fig. XI represents a fragmentary perspective view of one of the finned heat conducting elements disposed between the compartments of the cooling cabinet.

Fig. XII represents a detailed view showing the manner in which the finned heat conducting eie- 40 ments are attached to the cooling cabinet.

Fig XIII represents a detailed plan view of the radiator employed at the fresh air intake of the I Fig. XIV represents an end view of the fresh air intake radiator. I

Fig. XV represents a cross section of the fresh air intake radiator, taken as indicated by the lines XV-XV of Fig. XIV.

Fig. XVI represents a cross section of the fresh air intake radiator, taken as indicated by the 50 lines XVI-XVI of Fig. XV.

Fig. XVII represents across section of one of the openings'in the front of the cooling cabinet, taken as indicated by the lines XVIIXVII of N Fig. XVIII represents a perspective view of the humidifier.

Fig. XIX represents a side elevation of the humidifier with a portion thereof shown in vertical section.

Fig. XXrepresents a cross section of the humidifier, taken as indicated by the lines XX-XX of Fig. XIX.

Fig. XXI represents a detailed cross sectional view of a device used at the base of each refrigerant compartment for supporting the solid blocks of refrigerant; and,

Fig. XXII represents an enlarged cross section of the fresh air intake.

With particular reference to Figs. 1, II, and III of the drawings, there is, shown a railway passenger car of conventional type within which my invention is incorporated. The passenger space of the car is designated at P, and at each end thereof there is a bulkhead l. Between each bulkhead l and the adjacent end wall 2 of the car, there is a central passageway 3. At one side of the passageway 3 there is a lavatory L, and at the other side'of the passageway 3 there is a coolingcabinet C which is hereinafter more particularly described. In the space between the cooling cabinet C and the bulkhead I, there may be provided a wash basin 4 or other facilities depending upon the type of service inwhich the car is employed. Between the vestibule-and the central passageway 3 at each end of the car there is a door 5. Each end of the car, in the present example of my invention is a counterpart of the opposite end; and therefore, while the detailed description which follows is confined to the apparatus at one end of the car, it is to be understood that similar apparatus is preferably, though not essentially, provided at the opposite end.

The air cooling equipment incorporated in the railway car is adapted for use at all seasons of the year and the same circulatory system of air circulation is employed in' both summer and winter. During all seasons the passenger space P is substantially closed from the atmosphere by maintaining the side windows 6 closed and by keeping the end doors 5 closed except for the ingress and egress of passengers.

' Air circulation and replenishment As shown in Figs. 1, III, and V, at each end of the car near the roof thereof there is provided an air intake 1 with a damper 8 and fresh air filter l l therein through which fresh air from the atmosphere in regulated quantities is drawn into the interior of the car by means of a' fan 9 driven by a motor I0. As shown in Fig. XXII, the filter II is removable for purposes of cleaning or replacement, the intake 1 being provided with a removable cap member l2 having therein a spring clip l3 which releasably holds the filter II in place. During all seasons of the year the fan 9 is run continuously and serves not only to draw air in the desired quantity from the outside atmosphere through the intake 1 into the interior of the car, with incidental cleaning of the air, but also serves as the means for circulating used air in the car.

ir from the passenger space P is drawn by the fan 9 in parallel strata longitudinally of the car toward each end thereof and is admitted through a series of openings l4, 14a spaced at different elevations along the front of the cooling cabinet C, as clearly indicated in Fig. V. The. used air from the passenger space is then conthe mixing chamber II the combined used and fresh air is discharged by the fan 9 into a discharge duct l8 which is in the form of an elbow, as clearly shown in Fig. I, and which leads back to the passenger space P near the roof of the car above the central passageway 3.

Prior to the mixing of the used and fresh air in the plenum or mixing chamber 11, heat interchange is effected between the incoming fresh air and the circulating used air by means of the novel type of radiator l9 incorporated in the fresh air intake 1. The radiator I3 is shown in detail in Figs. XIII, XIV, XV, and XVI. It is made of heat conducting metal folded upon itself to the shape of a fan and affords a series of adjacent channels 20, 20a separated, by heat conducting vertical surfaces 28, the channels diverging inwardly from the side of the car. The.

with the vertically extending surfaces 28 guides I the fresh air from the atmosphere into and through the humidifier 24} Preferably also I provide a vbattle 29 adjacent to the fan 9, leading the used air from the car upward into the channels 20a of the radiator l9. It will be observed that all of the fresh air drawn by the fan 9 passes through the humidifier 24 into the plenum or mixing chamber II, the portion of the air received from the outside atmosphere passing through the conduit 22 and thence through the channels 20 into the humidifier 24. On the other hand, the used air from the passenger space of 50 the car, or at least the major portion of it, passes through the alternate channels 20a of the radiator I9 directly to the mixing chamber l1. While the used air and fresh air are separated in transit to the mixing chamber I1, the vertically disposed heat conducting surfaces 28 serve to promote heat interchange, cooling or' heating the used air in the car according ,to the difference in temperature between the exterior and interior of the car.

Air from the plenum or mixing chamber I1 is drawn into the fan 9 near its axis 30.' As shown in Fig. IV, the fan 9 in the present example of my invention has three impellers 3| and dischargesinto a connecting duct 32 divided vertically and horizontally by partitions 33, 34.

' The partitions 33, 34 serve as baffles well disbulkhead l near the roof of the car, and which is used only in thewinter season.

Air cooling The air cooling cabinet is in the form of a container divided into a series of tiered compartments 36, each adapted to accommodate blocks of solid carbon dioxide as represented at 31 in .each equipped with a handle 40 and adapted to be secured in place by dogs 4|. In an obvious manner. by removal of the closure members 39, the blocks of solid carbon dioxide 31 may be charged into their respective compartments 36. The blocks of solid carbon dioxide 31 each rest upon a support 42 which serves as a thermal control member. As shown more clearly in Fig. XXI, the thermal control member 42 is interiorly hollowed to afford gas pockets 43 and has openings 44 in the top surfacethereof which permit the gases of sublimation to enter into the pockets #33, thus forming a dead space of the desired thermal quality, separating the solid carbon dioxide from the metallic heat conducting surfaces-therebeneath. At the rear of each compartment 36 there is provided a spacing member 46 of wire mesh which serves as an abutment spacing the rear surfaces of the blocks of 'solid carbon dioxide at a distance from the rear insulating .wall 38 so as not to obstruct passage of the gases of sublimation from the compartment into the gas outlets 41.

From the outlet 41 of each solid carbon dioxide compartment 36 there leads a discharge pipe.

48a, 48b, 48c, 48d, 46c, which extends downward through the vertical air trunk l6 to the base thereof. The gas discharge pipes 48a, 46b, 48c, 48d, and 48e, as indicated in Fig. VIII,- join a common discharge pipe 49 located in the bottom passage I512. The common gas discharge pipe 49 is bent to the shape of a sinuous coil and preferably provided with finned heat conducting surfaces 50, thus serving .to absorb heat from that portion of the air from the passenger space of the car which enters through the opening |4a in'the cooling cabinet C and passes through the passageway I511 into the vertical air trunk IS. The common gas discharge pipe 49 ultimately leads downward through the floor of the car as indicated at and discharges to the atmosphere. It will be observed that that portion of the used air from the passenger space of the car which enters through the opening Ma and the circulating passage I5a of the cooling cabinet C is unobstructed in its flow.

At the front of the cooling cabinet 0 in advance of each opening l4 there is provided a louver 52 in the form of a metal plate perforated with slots 53. The lowermost louver 52;: disposed in advance of the lowermost horizontal passage I51; has considerablylarger slots 53a than those of the louvers 52. I

One form which the louvers 52 may take is shown in cross sectional detail in Fig. XVII.v As there shown the louver includes a cap 54 hinged at 55 and normally held in closed position by a spring clip 56. Between the outside slots 53 of the cap 54 and the inside opening l4. there is provided a suitable filter 51 which serves to clean the air as it passes into the cooling cabinet. The filters 51 are removably held in place by marginal strips 56, 59, and in an obvious manner they may be replaced or temporarily removed by swinging v 3 down the cap 54. The filters 51serve not only to collect foreign matter suspended in the air, but they purify the air as it passes 'into the cooling cabinet and prevent foreign matter from being deposited within the passages l5, l5a, thus avoiding unpleasant odors, and keeping the interior heat conducting surfaces clean. 2

In the openings l4 at the entrance to each air circulating passage l5 there are provided dampers 60, and additional dampers 60 are provided at the rear ends of the passages i5 controlling communication with the rear vertical air trunk Hi. The air trunk 16 is separated from the side wall 6| of the car by a relatively thick wall 62 of insulation. There are no dampers in the bottom- I most passage I 5a which is unobstructed. The dampers 66 are desirably of the form shown in Fig. X, and include flat plates 63 spaced in parallel relation by means of spacing members 64.

Each damper is mounted on an actuating shaft 65'. With this construction, when the dampers are closed, there are provided dead air spaces in series-from the front to the back of the cooling cabinet effectively insulating the cooling compartments 36 and cutting down to a minimum the rate of sublimation of the solid carbon dioxide. Immediately below the thermal control member 42 for the solid carbon dioxide blocks 31, there is a fiat metallic heat conducting plate 66, shown clearly in Figs. XI and XII. The plates 66 are bolted at their edges to angle irons 61 of the cooling cabinet in such manner as to be readily removable, and they are insulated from the angle irons 61 by means of leather strips 6.1a.

Each plate 66 has depending vertically therefrom a series of closely spaced fins 68. The fins 68 extend in substantially parallel relation across the air circulating passages IE to afford relatively large heat conducting surfaces through which .heat from the circulating air is absorbed incident to the passage of air through the cabinet.

As shown in Fig. V, at the bottom of each air circulating passage l5'there is provided an in clined plate 69 which slopes forwardly and downwardly toward the front of the cabinet and terminates in a trough-shaped gutter 16. The

plates 69 serve as drain plates causing the moisture deposited thereon to flow into the trough shaped gutter 10 from whence the moisture is discharged into drain pipes 1| which leaddowriwardly through the base of the cooling cabinet C and through the bottom of the car.

' Heating and humidification During the winter season the moisture content of the air in railway cars is usually low, and when the air is heated it becomes extremely dry, which is undesirable from the standpoint of health and comfort. Moreover, if too much moisture is added to the air in the car, and particularly 6 where moisture is added to relatively warm air, there will result in cold weather a deposition of moisture on the window glass and steel-work of the car.

With the arrangement of invention, the humidifier 24 is removed a considerable distance from the side of the car where fresh air is taken in at the intake 1, and moisture is applied to the incoming fresh air before it has had an opportunity to mix with the circulated used air.

air. By thus applying moisture to the incoming 75 The 70 radiator IS in the winter season causes the inj fresh air before it has had an opportunity to be fully warmed or mixed with the used air in the car, subsequent deposition of moisture is avoided or minimized.

The type of humidifier 24 which is preferably used in the railway car of my invention is illustrated in detail in Figs. XVIII, XIX, and XX. It comprises generally a casing 14, the base 15 of which is box-shaped and adapted to serve as a water receiving receptacle, and a continuous strip 16 of absorbent material which is wound around.

a series of top and bottom rollers TI. The strip 16 of absorbent material extends from one top roller downward into the water 18 around a bottom roller 11 and then upward again to the next adjacent top roller, and soon throughout the length of the humidifier. A top cover 19 and end walls 80 define with the base I a rectangular conduit with openings at front and back through which the air passes. The cross sectional area of this conduit corresponds to the area of the inner end of the radiator l9. The absorbent strip 16 servesfito draw water from the base by capillary attraction and to give up such water to the air passing through the humidifier, but it serves also to prevent surging of the water longitudinally of the humidifier. Toprevent lateral surging of the water there are employed bailles 8| which project downwardly and inwardly between the sections of the absorbent strip 16, these baffles substantially filling theintervals between,

the sections of the absorbent strip. With this construction, incident to swaying of the car or its sudden stopping or starting, water is prevented from surging or slapping out at the sides or ends of the humidifier.

For the purposes of maintaining a constant level of water in the humidifier 24, as indicated in Fig. XIX, there is employed a sealed water tank 82, shown most clearly in Fig. V, with a feed line 83 leading tothe base 15 of the humidifier. The tank 82 being sealed against the ad mission of air, waterwill flow from the tank to the humidifier 29 until it reaches a level co-incident with the top of the feed line 83. When the Water level in the base 15 of the humidifier falls by reason of evaporation, air will be admitted through the feed line 83into the tank 82, and additional water will flow from the tank to the humidifier, returning the water level in the latter to its original position. It will be especially observed that with the use of the above described construction there are no moving parts, floats or automatic valves, or other parts requiring ad'- justment. Operation of the humidifieris fully automatic and it is only necessary to charge the water tank 82 with a supply of water from time to time.

The humidifier 24 is ordinarily used only during the winter season. When solid carbon dioxide is used as a refrigerant for cooling the car, fresh air passes through the humidifier 24 in the customary manner, but it performs no useful function. However, the herein described system may be operated without solid carbon dioxide, with refrigeration obtained by evaporation of water in the humidifier, such a method of operation being particularly applicable in those regions where the prevailing humidity is low.

For the purpose of heating the air in the winter season, I may employ any conventional form of heater 35 disposed in the discharge duct 18, the particular construction of the heater being immaterial to the present invention. With the usual method of heating railway cars by direct cumulates.

radiation, there are zones'of extreme temperature difference in the passenger space of the car which is undesirable from a standpoint of comfort, and represents poor steam economy. With the heating system of the present invention, all of the air 5 in the passenger space is moved bodily and definitely toward the end of the car, and there are substantially no pockets in which dead air ac- Furthermore, there are no cold air regions in the vicinity of the floor, nor are con- 10 vection currents, such as arise from wide temperature differences, present within the passenger space. The passenger space is uniformly maintained at the desired temperature.

' Temperature control m The system of temperature control of the present invention avoidsth-e expense and careful attention which is characteristic of systems wherein the air circulation is effected by means which are continually starting and stopping. According to the practice of my invention, the fan 9 runs continuously, and there is always a definite and positive circulation of used air in the car, as

' air to pass through the intake when the damper is closed. In the present example of my invention, such means comprise-a series of perforations 85 extending through the damper. 8, though other means may obviously be employed. Moreover, when the inside dampers 68 of the cooling cabinet C are closed, there is still a positive and definite circulation of air through the cooling cabinet C. In that event all of the air passes through the opening Ma and the passage l5a at the bottom of the cabinet into the vertical trunk l 6 and from thence upward to the mixing chamber i1.

'As' clearly shown in Fig. VI, all of the inside dampers 68 are connected together for simultaneous opening and closing, and likewise the movement of the outside damper 8 follows the movement of the inside dampers 80. In the example illustrated, the shafts 65 of the inside dampers i extend through bearings 86, see Fig. IX, and through the insulated side walls 38 of the cooling cabinet to the exterior thereof, where they ter minate in sheaves 81. cabinet C there is provided a damper actuating shaft 88 which has at one end a sheave 89 connected by a belt 98 with'a sheave 9| associated with the intake damper 8. The damper actuating shaft 88 has at the opposite end a sheave 92 which is connected by a cable 93 with all of the individual damper operating sheaves 81, the cable 93 being wound around each sheave and terminating in a tension spring 94 which'is rigidly fixed to the railway car as indicated at 95. From the above description it will be apparent that all of the inside dampers 50, both those at the front and back of the cooling cabinet C, are mechanically interconnected with the intake damper 8 for simultaneous opening and closing. Associated with the fresh air intake 1 there is a thermostatic control means 96, preferably of the sylphon type, such means being responsive to changes in the temperature of the fresh air ad-' mitted from the outside atmosphere. Also, in the interior of the car, and preferably disposed in the discharge duct l8 in advance of the heater 35, there is an additional thermostatic control means 91 also of the sylphon-type. The outside sylphon 96 and the inside sylphon 91 jointly control the At the top of the cooling 50 opening and closing of the outside damper 8 and the inside dampers 60 through a cumulative action. ne.example of the mechanism by which this is accomplished is diagrammatically represented in Fig. VI. At the rear of the outside sylphon 96 there is provided a lever 98 pivoted at a fixed point 99. To the opposite end of the bell crank lever 98 there is attached a cable I00. The.

cable I00 leads to a lever arm IOI pivotally mounted on a fixed shaft I02. The lever arm IOI has integral therewith an arm I03 which is attached to one end of the inside sylphon 91. The opposite end of the sylphon 91 abuts against a bell crank lever I04, the two arms of which are of equal length. T0 the bell crank lever I04 there tends to increase the tension on the cable I05 turning the sheaves 81, 9 Im a clockwise direction against the pull of the spring 94. On the other hand, contraction of either sylphon 96, 91 tends to relieve the tension on the cable I05, slackening the same; and through the influence of the spring 94 the sheaves 81, 9I are all turned in a counterclockwise direction. Moreover, it is to be noted that the distance from the point of attachment of the cable I00 at the lever arm ml to the fixed shaft I02, as represented at y, is substantially threetimes the distance between the point of attachment of the cable I 05 at the bell crank lever I 00 to the fixed shaft I02, as represented at at. Hence,insofar as the opening and closing of. the dampers 8, 60 is concerned, expansion or contraction of the inside sylphon has three times the effect of expansion or contraction of the outside sylphon.

To illustrate'the operation of theitemperature control mechanism, let it be assumed that the outside sylphon 96 is set to operate between a range of temperature, say from 75 to 105 degrees F. Let is also be assumed that the inside sylphon 91 is set to operate between a range of temperature, say from 45 to '75 degrees F. Let it also be assumed that the dampers areoriginally adjusted so that they are closed when the air in the car'is in the vicinity of the basic predetermined temperature desired for comfort, and that this temperature is say 70 degrees F. vIn the winter season the outside sylphon 98 will be fully contracted and unaffected by changes in temperature. The inside sylphon 91 'will by itself regulate the opening and closing of both the outside damper 8 and the inside dampers 60. As the temperature inthe car is lowered below the basic temperature of 70 degrees F., the inside sylphon 91 will contract, causing a counterclockwise movement of the sheaves 81, 9|, and causing a counterclockwise movement of the dampers 60, 8 from vertical closed position to open position. Opening of the outside damper 8 and of the..inside dampers 60 in the manner described will cause a greater admission of fresh air from the outside atmosphere and a greater volume of used air in the car to be drawn intothe mixing chamber I1. Consequently more air will be passed over the heater 95, and the temperature of the air in the interior of the passenger space P will tend to rise. when the temperature has risen to the basic temperature of '10 degrees F., the inside sylphon 91 will expand and return to its original position, closing all the dampers.

In the summer season the outside sylphon 96 operates together with the inside sylphon -91 to effect modulated control of both the outside damper 8 and the inside dampers 60 in accordance with the following formula recognized by heating and ventilating engineers as applicable to the cooling of enclosures where people assemble:

In this formula, T represents the temperature desired to be obtained in the passenger space of the car; t represents the base temperature for maximum human comfort under average conditions, which is generally considered to be about '72 degrees F.;. and 0 represents the prevailing outside temperature. Under the above formula, assuming that the prevailing outside temperature is 97 degrees F., and that the base temperature is 72 degrees F., T, the temperature desired to be obtained in the passenger spaceequals:

or 81 degrees F.

It will be observed that the temperature control mechanism is so arranged as to follow the above formula. .The outside sylphon 96 is responsive to temperature changes in the outside atmosphere and modifies the action of the inside sylphon 91 in accordance with the temperature difference between the exterior and interior of the car, the outside sylphon 96 having one-third the effect of the inside sylphon 91 in causing simultaneous movement of the outside damper 8 and the inside dampers 60.

Accordingly, it will be apparent that the volume of air, both used air and fresh air from the atmosphere, flowing through the circulatory system of the car, is increased or diminished in response to changes in the interior temperature of the car, but such action is modified by the prevailing temperature difference between the air outside the car and that within the car.

Preferably the thermostatic control mechanism is initially arranged in such manner that in the summer season the outside damper8 and inside dampers 60 will close when the temperature in the mixing chamber is at, say 50 degrees F.,. and will open when the temperature in the mixing chamber is at, say 60 degrees F. In the winter season the dampers are set to close at a temperature of, say '10 degrees F. in the mix-- ing chamber, and to open at a temperature of, say 60 degrees F. in the mixing chamber. The above temperature values are given as examples, and other temperature ranges of operation are obviously obtainable with this system by utilizing sylphons 96, 91 of theproper travel for the desired temperature range, Further, while levers have'been employed to illustrate the cumulative effect between the action of the sylphons 96, 91, it is obvious that the same result may be obtained by direct action of one sylphon upon the other. It would, of course, be necessary to select the sylphons in such manner that an increase of 3 degrees F.'on sylphon 96 will produce the same effect as 1 degree F. on sylphon 91; In this manner, the combination of sylphons 96, 91 will automatically function to hold the inside temperature 1 degree higher than the base temperature for each 3 degrees rise in the outside temperature.

Moreover, it will be observed that precisely the,

same apparatus is employed throughout all seasons of the year and that no adjustment need be made between seasons, the only difference in the operation during the winter season as compared to that during the summer season being in the direction of rotation of the dampers from closed to open position and vice versa. Furthermore, at all seasons of the year and under all conditions of temperature, there is circulation both of fresh air from the outside atmosphere and of used air from the passenger space of the car, for the fan 9 is run continuously, the volume of air in the circulatory system being increased or diminished by modulated temperature control. Thus the present invention avoids the difiiculties characteristic of systems wherein elaborate electrical mechanism is employed to start and stop the air circulating means. In the summer season with the method of circulation described above, the solid carbon dioxide is conserved and its sublimation reduced to a minimum, and yet there is always a positive movement of good air through the circulatory system of the car.

While I have described my invention in some detail with reference to a specific'embodiment thereof in a railway passenger car, it will be apparent that various changes may bemade in the form of the specific apparatus described without departing from the spirit of my invention, and that certain features of the invention may at times be used to advantage without a corresponding use of other features.

Having thus described my invention, I claim:

1. A method of conditioning air in a railway car which consists in admitting air from the outside atmosphere at one end of the car into the interior thereof, drawing air from the passenger space toward said end of the car, there passing the air from the car in indirect contact with the air from the atmosphere with heat interchange, humidifying the air from the outside atmosphere and then mixingit with the air from the car, heating the mixed air, and discharging the mixed air back to the passenger space.

2. In a railway passenger car, apparatus for conditioning'air in the passenger space comprising a mixing chamber and a humidifier disposed in the-interior of the car, a fresh air intake leading from outside the car through said humidifier to said mixing chamber, an air circulating duct leading from the passenger space to said mixing chamber, said fresh air intake including a radiator having a series of air passages separated by heat conducting surfaces, certain of said passages conducting outside atmospheric air to said humidifier, and others connecting said air circulating duct to said mixing chamber, a discharge duct leading from the mixing chamber to the passenger space, a heater in said discharge duct, and means for drawing air from said circulating duct and fresh air intake into said mixing chamber and discharging the combined air through said discharge duct and heater into the passenger space.

3. In a railway passenger car, apparatus for conditioningair in the passenger space compris ing a fresh air intake leading from the outside .0 the interior thereof, a damper in said intake having means associated therewith for allowing a quantity of air to pass through the intake when the damper is closed, a discharge duct leading from the inner end of said intake to the passenger space of the car, air circulating ducts leading to the inner end of said intake, said ducts having dampers controlling the circulation of air therethrough, a fan for drawing air from the passenger space through said air circulating ducts and drawing additional air from said intake and discharging the combined air through said discharge duct back to the passenger space, and means connecting the damper of said fresh air intake with the dampers of said circulating ducts whereby all of said dampers open simultaneously and close simultaneously.

4. In a railway passenger car, apparatus for conditioning air in the passenger space comprising a fresh air intake leading from the outside atmosphere to the interior of the car, a damper in said intake having means associated therewith for allowing a quantity of air to pass through the intake when the damper is closed, a. discharge duct leading from the inner end of said,intake to the passenger space of the car, air circulating ducts leading to the inner end of said intake, said ducts having dampers controlling the circulation of air therethrough, a fan for drawing air from the passenger space through said air circulating ducts and drawing additional air from said intake and discharging the combined air through said discharge duct back to the passenger space, and an additional air circulating duct at all times unobstructed and leading from the passenger space of the car to the suction side of said fan.

5. In a railway passenger car, apparatus for conditioning air in the passenger space comprising a mixing chamber, a fresh air intake leading from the outside atmosphere to said mixing chamber, a damper in said intake, at discharge duct leading from the mixing chamber to the passenger space, an air circulating duct leading to said mixing chamber and having a damper controlling the circulation of air therethrough, a fan for drawing air from the passenger space through said air circulating duct to the mixing chamber and drawing additional air through said intake to the mix-' ature of the air in the car, said thermostatic control means being interconnected for cumulative action and operable to simultaneously open and close the dampers aforesaid with the latter thermostatic control means having substantially three times the effect of the former.

6. In a railway passenger car, apparatus for conditioning air in the passenger space comprising a mixing chamber disposed near the end of the car, a fresh air intake leading from outside the car to said mixing chamber, a discharge duct leading from said mixing chamber to the interior passenger space, a heater in said discharge duct, a humidifier for applying moisture to the fresh air, said humidifier being disposed between said fresh air intake and mixing chamber, means for drawing air from the passenger space to said mixing chamber, there causing it to be combined with humidified air from the fresh air intake, and discharging said mixed air back. into the passenger space through said discharge duct and heater,

and means whereby the re-circulated air from the passenger space is passed in indirect contact with and in heat-interchanging relation to said fresh air preparatory to the fresh air passing through the humidifier.

WILLIAM J. MADDEN. 

